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Flight Controller Data Analysis Series Tutorials -- Part 7
2803 0 2017-9-29
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Content:

1.        Flight Controller Data Analysis Series Tutorials – Exporting the Flight Controller Data and Introducing DataViewer
2.        Flight Controller Data Analysis Series Tutorials – Locating the Crash Data
3.        Flight Controller Data Analysis Series Tutorials – Introduction to Coordinate Systems
4.        Flight Controller Data Analysis Series Tutorials – Introduction to Attitude Mode and Crash Cases
5.        Flight Controller Data Analysis Series Tutorials – Stopping Motors by Conducting the Combination Stick Command (CSC)
6.        Flight Controller Data Analysis Series Tutorials – Drone Under Control Crash Cases
7.        Flight Controller Data Analysis Series Tutorials – Compass Interference Cases



7.        Flight Controller Data Analysis Series Tutorials – Compass Interference Cases

The compass provides navigation information to the drone. It plays a key role in controlling the drone’s position and speed. It gets the yaw angle data of the drone by measuring the Earth’s magnetic field. However, the Earth’s magnetic field is very weak and can easily be interfered by the electromagnetic field. Strong magnetic fields, high-voltage lines, buildings, etc. will interfere with the Earth’s magnetic field and affect the normal flying of the drone. You can check the mode_m value in DataViewer to determine whether the drone’s compass is interfered during flight.
The magnetic field measured by the compass can be indicated by a three-dimensional vector  .
41.png
e_mode_m in DataViewer refers to the length of this vector, that is
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In a flight, the Earth’s magnetic field is basically constant, so the magnetic field measured by the compass should also be constant. If e_mode_m in DataViewer changes significantly, the magnetic field around the drone may be affected by the environments.


After the compass in the drone is calibrated, e_mode_m in DataViewer will be 1500. In figure 7.1, e_mode_m’s value falls between 1500 and 1600 before 496s, but it changes greatly in the following ten seconds. In common cases, if e_mode_m’s value increases or decreases by 500, the compass suffers from strong magnetic interference.

Flying experiences will be affected if the compass is interfered severely, as the drone cannot hover accurately, but it is circling in place while hovering, or even crash. If the compass is interfered or the yaw angle of the drone cannot be controlled when the drone is flying close to some objects, move away from the objects immediately, or check whether there are large currents flowing around the compass module.
Besides, the compass of the A3 or N3 is built into the GPS module, as it will not be easily interfered by the currents of the third-party airframes after the GPS module is raised up.


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Figure 7.1


2017-9-29
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